German Patent No. 43 17 656 C2 describes a key-actuated circuit breaker having a leading auxiliary switch, in which the auxiliary switch is arranged as a pre-switch between the turn-on key and the switching contact, with an increased opening path compared to the stroke of the turn-on key being achieved for the main contacts using a rocker or transfer lever for the auxiliary contacts. This method cannot be used for rotation activated circuit breakers, in which the main contacts are actuated by a rotary actuating mechanism via a breaker mechanism. In such circuit breakers, there is also the danger of creeping contact actuation of the auxiliary switch, which may result in uncontrollable contact overlaps between main contacts and auxiliary contacts when interacting with an undervoltage fuse, for example.